One knows of very many types of boring attachments. Some are commonly called "boring heads". In this case, the cutting tool can be moved and the dimension obtained, over relatively long distances, by any guide system whose moving part is moved by a screw and nut system. Consequently, if one wishes to change the dimension of the bore to be machined, one moves the cutting part or "insert" by an amount corresponding to the chip removal desired.
One can imagine that, in this type of attachment, there is play between the taper for connecting the attachment to the spindle of the machine and the point or insert, due to the stacking of several parts, which can cause vibrations during cutting. The other disadvantage of this type of attachment is that it is expensive and relatively brittle.
One knows of other types of boring attachments called "expanding boring tools". Dimensions are obtained by means of the total deformation of the entire point. Consequently, in this precise case, there is no movement of the cutting edge of the boring tool in relation to the axis of rotation of the attachment, but there is deformation of all the cutting edges in relation to the axis of rotation.
There is also a third type of boring attachment, called "boring bars", which have at their end a cutting tool integrated into an extending system. This assembly is housed in a radial bore.
The objective sought, according to the invention, was to overcome the disadvantages and limitations of the above-mentioned attachments.